1. Field of the Invention
The invention relates generally to particle analyzing and sorting apparatus and more particularly is concerned with apparatuses in which studies may be made of particulate systems using the impedance sensing principle and optical measurements.
2. Description of Prior Art
Since its conception in the early 1950's, the principle of particle counting and sizing invented by Wallace H. Coulter has resulted in numerous methods and flow-through apparatuses for the electronic counting, sizing and analysis of microscopic particles, which are scanned in a fluid suspension, as shown by the pioneer U.S. Pat. No. 2,656,508 to Coulter. In this prior art arrangement, a D.C. electric current flow is established between two vessels by suspending electrodes in the respective bodies of the suspension fluid. The only fluid connection between the two bodies is through an orifice; hence, an electric current flow and field are established in the orifice. The orifice and the resultant electric field in and around it constitute a sensing zone. As each particle passes through the sensing zone, for the duration of the passage, the impedance of the